The Pennsylvania Coal Workers' Respiratory Disease Program (CWRDP) is a Federally funded pulmonary rehabilitation program with objectives of preventing or controlling disease progression and reducing numbers and lengths of respiratory hospital days. This non-concurrent prospective study examines a cohort of 1000 coal miners with initial CWRDP enrollment in 1979. The miners' clinic records will be reviewed for a 5 year period. The study has the following specific aims: 1) To determine if the treatment program administered by the Pennsylvania CWRDP is associated with reduced morbidity as measured by respiratory hospital days. The effects of treatment on hospital days from respiratory illness, pulmonary function, chest radiography, and arterial blood gases will be observed and evaluated using multivariate analysis. The coal workers' clinic records of admission due to respiratory illness will be validated by a review of local hospital discharge records. A subsample of the coal workers' hospital medical records will be abstracted for a period of 5 years pre and 5 years post program enrollment to compare pre and post program pulmonary function status and respiratory hospital days. 2) To compare the differences in morbidity between coal miners electing treatment and those not electing treatment. Of miners initially evaluated, stratification will be done by level of pulmonary function (i.e. good: FEV-1/FVC greater than 69%, intermediate: FEV-1/FVC 40 to 69%, and poor: FEV-1/FVC less than 39%). Within each strata, treatment enrollees will be categorized separately from those not electing treatment. The number of hospital days and rate of ventilatory function decline will be compared in the treated and non treated by utilizing hospital discharge records for respiratory illness. 3) To determine if the benefits of reduced hospital days from respiratory illness exceed the Program implementation costs. Program implementation costs will be obtained from clinics participating in the Program. Benefits will be measured by the reduced hospital days from respiratory illness expressed in dollar terms. The null hypothesis to be tested is as follows: No significant difference exists in morbidity between treated and non treated groups.